Modified Adsorption Energies on Single-Layer IrO2 and RuO2 Films of IrO2-RuO2 Heterostructures: Localized Effect of Subsurface Metal-Oxygen Ligands

Document Type

Article

Publication Date

7-4-2025

Abstract

Rutile oxides offer a promising platform for creating and studying mixed metal oxide surfaces for catalytic applications. RuO2 and IrO2 have been used for the electrochemical oxygen evolution reaction and alkane oxidation reactions, and they have similar lattices which promotes the synthesis of layered structures (e.g., IrO2/RuO2) and IrO2-RuO2 solid solutions. Their low-energy surfaces, the (110) plane, expose rows of coordinatively unsaturated metal atoms (Mcus) which act as binding sites during catalysis. Here, we generated single-layer IrO2 films on RuO2(110), single-layer RuO2 films on IrO2(110), and their thick-film counterparts, and studied their binding properties using molecular N2 and dissociative O2 adsorption. Temperature-programmed desorption measurements and complementary density functional theory calculations and electronic structure analysis show that the binding properties of Mcus sites are strongly influenced by the identity of cations in the subsurface beneath the binding site (Msubcus), such that Msubcus identity influences binding as much as the identity of the Mcus binding site itself. Our analysis shows that these strong effects of the subsurface cations originate from localization of the σ system involved in adsorbate binding, and the resultant accumulation of charge on the subsurface O atom beneath the Mcus site upon adsorbate binding. Replacing Ru with Ir at the subsurface sites stabilizes this charge and strengthens the binding of both N2 and O with the Mcus site. We discuss a computational alchemy model that can explain both the site and ligand effects of chemical binding on IrO2/RuO2 heterostructures and is extendable to other mixed metal oxide and metal alloy surfaces.

Publication Source (Journal or Book title)

ACS Catalysis

First Page

11134

Last Page

11149

This document is currently not available here.

Share

COinS